Sir Richard Branson today offered a $25m (£12.8m) prize for scientists who find a way to help save the planet from the effects of climate change.

Flanked by the former US vice-president Al Gore and other environmentalists, the boss of Virgin Atlantic airlines called for scientists to come up with a way to extract greenhouse gases from the atmosphere.

Describing the prize as the largest ever offered, Sir Richard compared it to the competition to devise a method of accurately estimating longitude. He denied that being the head of an airline prevented him from being concerned about climate change.

"Let's confront the airline question. I have an airline. I can afford to ground that airline today. My family have got businesses in mobile phones and other businesses, but if we do ground that airline today, British Airways will just take up the space.

"So what we are doing is making sure we acquire the most carbon dioxide-friendly planes. We're making sure that 100% of profits we make from our transportation businesses are put back into things like the prize we've offered today."

Sir Richard said he had been influenced by James Lovelock, who developed the Gaia Theory, which suggests that the world may already have crossed a "tipping point".

"Today we have a threat. Still we have to convince many people that the threat is urgent and real and there is no superhero. We have only our own ingenuity and we have no hope of a meaningful solution unless we find a way to work together," he said.

Mr Gore said global warming was man-made and was akin to the planet suffering from a "fever as a result".

"It is a challenge of moral imagination of humankind to accept the reality of the situation we are facing. We are not used to this. There is nothing in our prior history that equips us to think that we could be in the process of destroying the inhabitability of the planet," he said.

Humans had slipped into a way of thinking that was centred on "short-term gratification", and now faced the challenge of "transforming ouselves and changing the structures of everything we do", he said.

Reacting to the launch of the prize, Tony Jupiter, the Friends of the Earth's director, warned against wasting time waiting for new innovations.

"Technology has an important role to play in tackling climate change," he said, "and Sir Richard's initiative may encourage innovators to develop a wonder technology which takes carbon dioxide out of the atmosphere.

"But many of the ways of tackling climate change, such as energy efficiency and renewables, already exist, and it is essential that these are implemented as soon as possible. We cannot afford to wait for futuristic solutions which may never materialise."

"Sir Richard must also look at his business activities and the contribution they make to climate change. The world will find it very difficult to tackle climate change if air travel continues to expand and space tourism is developed."

In September last year Mr Gore and Sir Richard appeared on US television to discuss the Virgin boss's pledge to invest £1.6bn in alternative fuel development.